Mental health, psychosocial, and peacebuilding supports are badly needed to support war-affected children in diverse countries. To meet the scale of the needs in an accountable manner, it is essential to have a broad vision of systemic supports for populations of war-affected children. This article, which introduces the 2nd Special Issue on Children and Armed Conflict, outlines 3 pillars of systemic supports for war-affected children: comprehensiveness, sustainability, and Do No Harm. It shows how supports should be multileveled, resilience-oriented, multidisciplinary, tailored to fit different subgroups, and attentive to issues of policy and funding. The achievement of sustainability requires additional attention to building on existing supports, adapting to the local culture and context, focusing more on capacity building than on projects, greater power sharing with local actors, embedding supports in local institutions, and strengthening the evidence base regarding sustainability. The Do No Harm principle requires self-critical practice and the prevention and management of unintended harms related to issues such as discrimination, the use of orphanages as the first resort for war orphans and separated children, raised expectations, dependency, and picking open the psychological wounds of war-affected children. With these pillars as a framework, the article ends with a brief overview of the 8 articles that comprise this 2nd Special Issue.